This proposal is for the Boston Clinical Center to continue to annually examine the 102 currently enrolled COSMICC participants (only 8 subjects have been lost to follow-up since enrolled in 1997-98) for an additional 5 years, for a total follow-up period of 14 years following the COSMICC2 protocol. The data collected from this center will be used to address the specific aims described in more detail in the Chair application and summarized briefly here: 1) to use mathematical functions (the Gompertz function and others) to model myopia progression in the 58% of COSMICC subjects whose myopia is still progressing, and to develop predictive models and test hypotheses based on previously identified risk factors (such as age, ethnicity, parental myopia); 2) to test 4 hypotheses related to environmental risk factors for myopia progression and stabilization and axial elongation in this well-characterized cohort of myopes; and 3) to test 3 hypotheses related to the association of oxial elongation and myopia progression with intraocular pressure, central corneal thickness, and macular thickness in COSMICC subjects. The high prevalence of myopia (25% of the US adult population) and its prominence as a public health problem (risk factor for conditions that can cause vision loss and blindness) emphasize the importance of gaining increased understanding of mechanisms underlying progression and eventual stabilization, so that in the future myopia might be limited to low levels. Better understanding of the factors predictive of myopia progression and stabilization also will help guide selection and timing of interventions as well as target those groups that may benefit the most from treatment.